The use of composite materials in the design of aeronautical structures began timidly after the Second World War. The first materials, basically glass fibers embedded in polyester resins, were used in the design of secondary structure elements, such as radomes, protection of antennae and hulls. The constant evolution of the developments of new materials has led to the progressive use thereof in more components of the airplane.
Twenty-five years of accelerated evolution, both of the properties of the material and the knowledge of their behavior, have passed since the milestone of the certification of the first primary structure element of a passenger airplane completely designed with composite material was achieved in the 80s decade until today, when the launch of the design of the greater part of the structure of an airplane in composite material is studied.
The composite materials that are most used in the aeronautical industry consist of fibers or fiber bundles embedded in a matrix of thermosetting or thermoplastic resin, in the form of a preimpregnated or “prepreg” material.
Without the intention of being thorough, the advantages of composite materials can be specified in three essential aspects:                Their high specific strength with respect to metallic materials. It is the strength/weight equation.        Their excellent behavior before fatigue loads.        The possibilities of structural optimization hidden in the anisotropy of the material and the possibility of combining fibers with different orientations, allowing the design of the elements with different mechanical properties adjusted to the different needs in terms of applied loads.        
Processes for designing aeronautical structures taking advantage of said optimization possibilities are not known in the prior art and the present invention intends to solve this shortage.